The present invention relates to an improvement of an apparatus for processing semiconductor substrates (hereinafter referred to as wafers), or any other plates, such as glass plates. More particularly, the present invention relates to an improvement of an apparatus for use, wherein the apparatus is adapted for use in a rinse processing and a dry processing.
To dry wafers by rotation thereof, there have been several proposals, among which Japanese patent application Laid-Open No. 57-183038 shows such an apparatus as depicted in FIG. 4, which is discussed in detail below.
The well known apparatus depicted in FIG. 4 comprises a housing 101 which defines a drying chamber 102 therein. A rotary member 106 is rotatably provided in the chamber 102, and is fixedly supported by a shaft 109. On the rotary member 106 a couple of wafer cases 107 are detachably mounted, wafers to be processed being stored horizontally in the wafer cases. A lid 103 is provided on the top of the housing 101, the lid 103 having an opening 104 through which dry air is introduced into the chamber. The conventional apparatus further comprises a cylindrical inner wall 108 extending downwardly from the lid 103 up to slightly below the upper margin of the rotary member 106 so that the upper margin is surrounded by the inner wall 108. When a dry processing is carried out, the rotary member 107 in which wafers to be processed are stored is rotated at high speed, during which dry air is introduced into the chamber, through the opening 104. The dry air introduced is used for drying the wafers, and thus-used air is expelled through an exhaust duct 105 which is pneumatically connected to the chamber. The flow of air is depicted by arrows in FIG. 4.
In the conventional apparatus as mentioned above the cylindrical inner wall 108 is intended to function as a barrier to prevent undesirable water and dirt from entering into the inside of the rotary member 106, that is, from contaminating the wafers to be processed thereby.
However, there remains a problem that eddy flows denoted by the numeral 103a may be caused in the upper peripheral portion within the chamber denoted by the letter C, where desirable water and dirt expelled from the rotary member 106 will accumulate and disadvantageously enter into the inside of the rotary member through a space between the inner wall 108 and the rotary member, because the rotation thereof causes a negative pressure inside the member 106. The wafers to be processed and stored in the cases 107 can be contaminated and spoiled.